Radio recorder



Sept. 3, 1940. J. r. POTTER RADIO RECORDER vFiled July 8, 1938 Sheets-Sheet 1 INV'ENTOR F82 www@ Zigi.'

Sr/vcf/RoNousMaraR Sept- 3, 1940- J. T. POTTER 2,213,886

RADIO RECORDER Filed July 8, 1938 2 Sheets-Sheet 2 v BY ATTORNEY Patented Sept. ."i, 1940 UNITED f STATES PATENT OFFICE i RADIO REooRnEn John T. Potter, Brooklyn, N. Y.

Application July 8, 1938, Serial N o. 218,142

, v Claims.

My present invention relates to methods of and means for making permanent records of the listening habits of radio receiver users.

One object of my present invention is to pro- 5 vide a system for recording the time and wavelength or frequency of operation of a radio receiver of the superheterodyne type without requiring mechanical connections to the radio receiver.

Another object is to provide such a recording device which may be used even with the smallest midget receiver where space limitations prohibit the use of a mechanically coupled recorder.

Still another object -is to minimize the appare l5 ent and visible changes required in adapting a radio receiver to operate such a recorder.

A further object is to provide a system for recording the time and wavelength of operation of a radio receiver of the superheterodyne type in which the adjustments in the recorder to 2 adapt it to any particular receiver are minimized so that in most cases changing a coil and pad` diate frequency of the receiver is all that is.

necessary. 25 These and other objects of the inventionfwill be apparent from the following description and in particular from the detailed description of the invention as shown in the gures of the drawings.

In the past the time and wavelength of operation of radio receivers have been recorded by mechanical devices. In general these devices comprise pens or other marking means moved across a paper record sheet by a mechanical 35 mechanism connected to the tuning condenser oi the radio receiver. In my co-pending application, Serial No. 112,459 entitled Recording device for radio receivers,-i'iled on Nov. 24, 1936, I have shown an improved mechanically coupled 10 but electrically operated recorder in which certain limitations of past recorders have beenovercome. In this present system, however, some of the remaining limitations of my mechanically coupled system have been overcome by a purely 1b5 electrically coupled device. Some of the elements and operations of the above referred to system are retained in my present system but I have discovered means for determining the wavelength setting of the radio receiver by purely electrical means.

' My present system consists of a tuned circuit electrically coupled to the oscillator of the superheterodyne receiver upon which records are to be made. This tuned circuit is connected to a thermionic vacuum tube detector which in turn operates a relay when sufficient voltage appears across the tuned circuit. This relay closes a circuit energizing the marking means of therecording system. 'I'he tuned circuit consists of a coil. 5 a fixed padding condenser and a continuously variable tuning condenser. The tuning condenser is continuously rotated or oscillated by a synchronous motor which drives the paper tape of the recorder and which may also run a clock. 10

On the tuning condenser shaft is located a contactor which closes the recorder marking cirf cuit in 'conjunction with contacts located at predeter mined points of angular displacement of the condenser rotor. By proper choice of the coil 15 and padding condenser the tuned circuit may be made to resonate with the receiver oscillator at angular positions of the tuning condenser corresponding to predetermined receiver response frequencies for any commonly used intermediate frequency. Thus when the radio receiver is operating at any of the predetermined frequencies. the simultaneous closing of the contactor circuit and the relay, due to recorder circuit resonance with the receiver oscillator, causes a mark to be made on the recorder tape in a column predetermined to be that of the station being received.

In most cases the recording system may be adapted to superheterodyne receivers with various intermediate frequencies merely by using the :appropriate coil and padding condenser.` A

marking stylus energized directly from the relay circuit may be used to record, without going through the selector switch, so that periods of operation of the receiver on other than the predetermined wavelengths is indicated.

Fig. 1 shows a circuit diagram of oneform df my present invention.

Figs. 2, 3 and 4 show various mechanical details of the present recorder.

Figure 5 shows one form of selector arrangement.

In Fig. 1, I have shown in block diagram a conventional superheterodyne radio receiver l with fragments of the receiver circuit necessary to show the method of electrical connection of my present recording system. Receiver i may be adapted to pick up signals in any well known manner as by means of antenna 2 and ground 3. Ground designation 3 is also used to indicate o common low potential or ground points in the receiver and recorder circuits. The recorder utilizes the oscillator frequency ofthe receiver to indicate the station being received. One method of coupling t0 the recorder is through a coupling 55 and connecting leads to coil 9 at points 6 and 6.

' Other methods of coupling are available as for instance, coil 9 may be connected in series with plate 56 by connections made at the remote or low end of plate coil 9.

In the recorder the oscillator current flowing in coil 9 inducesa voltage in coil I9. Coil I9 is tuned by a synchronous motor driven tuning condenser I4 and is padded by a series condenser I I. Coil I9 and condenser I`I are chosen to track with the oscillator of the receiver so that by changing them to suit the intermediate frequency of the receiver, condenser I4 will cover the various oscillator frequency ranges .used to cover a given carrier frequency band as for instance the broadcast band. Condenser I4 isy continuously rotated or oscillated by its synchronous motor drive and, if the receiver is operating in the desired band, at some point of rotation the circuit I9-I I-I4 will resonate to the receiver oscillator frequency and a sharply increased voltage will be impressed on control grid I9 of the detector tube I5. While not limited to such, detector tube I5 is shown as a pentode with heater 2l, cathode 29, control grid- I9, screen grid I8, suppressor grid I1 and plate I6. Grid bias battery 23 is connected to grid I9 through grid leak 22 although other bias means may be used. The various voltages in the systemare adjusted so that when the resonated oscillator voltage is impressedv on grid I9 an increased current flows to plate I6 through the winding of relay 26 suflicient to attract the relay armature 21 closing the relay contacts 28 and 29. Contacts 28 and 29 are connected in series with primary 3l of the recorder energizing transformer3I-32, the radio receiver onoff switch 33 and the leads 35 to a source of alternating current power for the receiver. Seoondary 32 is connected to energize a recording stylus 45 and switch 31 and one side of styli 46, 41, 48, 49 and 59. Switch contactor 31 is coupled to condenser rotor I4 by a mechanical link 38 and thus contactor 31 closes circuit with the various contacts 39, 49, 4I, 42 and 43 at predetermined settings of condenser I4. Contactors 39, 49, 4I, 42 and 43 are adjustable and are adjusted so that'contactor 31 contactsthem at points of rotation corresponding to tuned circuit I9I4 response points corresponding to frequencies of the 'receiver oscillator in turn corresponding to desired stations tuned in. Contacts 39, 49, 4I,

,42 and 43 are connected to styli 46, 41, 48, 49 and 59 respectively. Hence with receiver I turned on stylus 45 will be energized once upon each excursion of the tuning condenser I4 and if the station tuned in on the receiver is one of the stations to be recorded one of the other styli 46, 41, 48, 49 or 59 will be energized'. `If the statlon'tuned in on the receiver is `not one of the desired stations only stylus 45 will be energized.

In order to produce a record with a time axis, a paper tape 44 or other suitable recording sur face is moved with respect to the styli by means of a synchronous motor 55 which also drives by mechanical coupling 53 the link 38 operating lswitch 31 and condenser I4. 'I'he paper tape may Thus tape 44 moves at a predetermined rate` and a series of marks'are produced showing total time `of operation of the receiver and another series marks `will be produced showing operation of the. receiver at any of a number of predetermined frequencies.

Fig. 2 shows one mechanism for oscillating condenser I4. A condenser which is rotatable through 360 degrees may be continuously rotated but a condenser limited to 180 degrees of rotation must be oscillated through this 180 degree range.

Condenser I4 rotated on a shaft 12 which also carries the contact ar'm 31 of the selector switch is driven by a pulley 1I through a belt 13 from a second pulley 14. Pulley 14 is mounted on a shaft 16 and is made to rock back and forth through a small angle by means of cam 18 operating in the slt 11 in pulley 14. Cam 18 is mounted on shaft 16 which is rotated continuously by means.

.mechanism Contacts 39, 49, 4I, 42 and 43 are adjustable screws movable in the arc shaped slot y 83 in order that they may be pre-set for desired its position relative to the condenser I4 rotor a clamp 66 is provided with a bar 65 fitting in a hole 6.4 of 4body 51. Clamp 66-has a slot 69 which fits over a part of the condenser -frameor other suitable part of the recorder as shown' hyp-,19.

Set-screw 68 permits adjustment and fixing of the clamp 66 on frame 19 and set-screw 61- permits adjustment and fixing-of clamp 66 on bar 65. Thus body 51 is adjustable over a wide range of positions and may -be finally flxedmin any desired position. 1 'M' Fig. 4 shows a detail drawing of contactor 81. It consists of a spring contactor 31 and setscrews 19 and 89 vfor securing it to condenser shaft 12.

In Fig. 5 is shown another selector arrangement. Two selector switches 31 and 83 are mechanically connected together and motor driven thru link 38 as before. Switch 31 having contacts 39, 49, 4I, 42 and 43 is the stylus selector as above. the same number of contacts as switch v31 and atv corresponding angular positions. Switch 83 contacts 84, 85, 86, 81 and 88 correspond to switch 31 contacts 39, 49, 4I, 42 and 43. Between contact 84 and ground 3 is connected a fixed tuning condenser 89 ofla value to tune coil I9 padded by condenser II to a desired receiver oscillator frequency corresponding to one of the rcarrier frequencies which it is desired to record.

adjustable for rapid changing. Condenser 93 is The second switch 83 is providedL withv shown as being variable in case an'easily adjustable recording position is desired.

In Fig'. 1 stylus transformer v3I--32 is shown energized thru the receiver on-off switch 33 as a preferred arrangement. If the heater and or plate voltage for tube I5 is obtained from the receiver circuits transformer 3I-32 may be connected to the power line thru relay 21 at all times since relay 21 will only 'be energized while'the receiver is turned on.

While I have shown and described one embodiment of my invention it is not intended to limit it to the particular arrangement shown but only to arrangements within the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. In a device adapted to record the tuning positions of a superheterodyne radio receiver including an oscillator, the combination of, a thermionic vacuum tube including at least a cathode, a grid and an anode, an inductance periodically tuned over a band of frequencies by a rotatable, motor-driven variable condenser connected between said grid and cathode, means for moving a record sheet at a constant rate to provide a time base, a plurality of recording styli mounted in spaced relation and bearing upon said sheet, a multipoint switch, means for actuating said multipoint switch in synchronism with said condenser, means for energizing said styli from said anode selectively thru said multipoint switch, and an electrical coupling circuit between said radio receiver oscillator and said tuned inductance whereby said vacuum tube energizes said multipoint switch whenever it is tuned by said variable condenser to .a frequency corresponding to that of said oscillator.

2. In a device adapted to record the frequency of an alternating current signal, the combination of an inductance periodically tuned to a plurality of frequencies by a rotatable variable condenser, a plurality of styli, a multi-point selector switch, separate electrical circuits connecting said styli with predetermined points of said selector switch, a thermionic vacuum tube interposed between said inductance and means for energizing said styli through said multi-point switch, means for moving a record surface at a substantially constant rate past said styli to provide a time base, means for introducing at least a part of said signal into said tuned inductance, and means for operating said selector switch in predetermined relationship with said condenser whereby said vacuum tube energizes said multipoint switch whenever it is tuned by said variable condenser to a frequency corresponding to that of said signal.

3. In a device adapted to record predetermined tuning points of a superheterodyne radio receiver ncluding a variable frequency oscillator, the combination of, a thermionic vacuum tube including at least a cathode, a. grid and an anode, an inductance tuned by a rotatable variable condenser connected between said grid and cathode, a plurality of recording Styli mounted in spaced relation and bearing upon a record sheet, a multipoint rotatable switch in series with at least a portion of said styli, an electrical coupling circuit between said oscillator and said tuned inductance, means for rotating said'condenser and switch and moving the record ysheet in predetermined mutual relation and means connected to said anode for energizing said styli through said switch in response to oscillator derived signals on said grid.v

4. In a device adapted to record predetermined modes of operation of a superheterodyne radio receiver including a variable frequency oscillator, the combination of, a thermionic vacuum tube including at least a cathode, a grid and an anode,

an inductance tunable by a plurality of condensers, connected between said grid and cathode, a multipoint switch for connecting said condensers in parallel with at least a portion of said inductance for tuning said inductance to predetermined oscillator frequencies, a plurality of styli mounted in spaced relation for recording upon a record sheet, a second multipoint switch in series with at least a number of said styli, an electrical couplingcircuit between said oscillator and said inductance, means for operating both of said switches and for moving the record sheet in predetermined mutual relation, and means connected to said anode for energizing said styli through said second switch in response to oscillator signals to which said tuned circuit responds.

5. In a device adapted to record the oscillator frequency of a superheterodyne radio receiver, the combination of, a selective search means comprising an inductance tuned by a succession of predetermined capacities to a plurality of predetermined oscillator frequencies, a selector for selectiiig said capacities, electrical coupling means for connecting between the oscillator of said receiver and said inductance to introduce signals to be recorded into said tuned inductance, a synchronous motor for operating said selector at a predetermined rate, and a recording means for recording the presence of signals on said predetermined frequencies including an electrically 0perated device for marking on a record surface, a multi-point selector operated in point-by-point synchronism with the 'lrst said selector by said motor, and a rectiiler responsive to the presence of tuned signals in said inductance for operating said marking device thru said multi-point selector in accordance with said signals.

JOHN T. POTTER. Y 

